Known to us at the time as the FerPerComSoc board (Ferranti Personal Computer Society who, I believe, designed it), this was something special. I bought this as a kit via the Merseyside group. The PCB could be cut where the 78-way connector is. Left as a single board the smaller part to the RHS was a buffer board for a Nascom-1. The 78-way connector then became one end of a Nas-Bus, into which other cards could be plugged. If the board was split then you could use just the larger portion with a Nascom-2.